Conical spiral spring



Dec.27,1932. SGROSS 1,892,339

CONICAL SPIRAL SPRING Filed Aug. 3, 1928 F lg. 4;

W w W w \/A w -Q T al Patented Dec. 27, 1932 PATENT E'FICE SIEGFRIEDGRGSS, OF ESSEN, GERMANY, ASSIGNOR T FRIED KRUPP AKTIENGESELL- SCHAFT,OF ESSEN-ON-THE-RUHR, GERMANY CONICAL SPIR'AL SFP-,ING

Application filed August 3, 1928, Serial No.

The invention relates to conical spiral Springs and consists primarilj,7in winding the spring with such a pitch, that all of the spring threadscome at least approximately simultaneously to abut on one abutment ofthe spring, when the ultimate load is attained.

In order that the invention may be more easily understood, an embodimentof the new conical spiral spring is illustrated in the drawing whichaccompanies and forms part of this specification. In this drawing Figure1 is an aXial section through the spring, while Figures 2 and 3 areelevation and top v ew, respectively, of the steel band intended for tie manufacture of the spring.

According to the invention the spring is wound with such a pitch, thatthe distance of each point, e. g. the point P, of the narrow surface alturned toward the spring` abutment B, of the steel band A forming thespring in unloaded condition, from this abutment as, e. g. a is equal tothe distance this point has to travel under the action of the ultimateload of the spring. This design results in the fact, that incontradistinction to the well-known conical spiral Springs, in which theindividual coils come successively to abut on the one spring abutmentupon the spring being compresscd, all of the spring coils simultaneouslyabut on the abutment upon the ultimate load being attained, so that allof the coils take part in accumulating the deformation work during thewhole stroke of the spring. Besides, a linea-r relation exists in thepresent conical spiral spring between the load of the spring and itsstroke, which relation is in many cases dcsired and does not actuallyexist with the hitherto known conical spiral Springs. Fig. 2 illustratesthis relationshlp, whereln the spring 1s shown' 1n developed form. Notuntll the maximum load is exerted u Jon the s orinO` does the orb tion mcoincide with a llne NN', representing one of the spring abutments. Inthe case when but half of the ultimate load is exerted upon the spring,the displacement of the lower edge of the spring corresponds to the linePQ, wherein the point Q, is equidistant 297,209, and in Germany August29, 1927.

from line NN' and m. The displacement of the other portions of thespring is relatively similar, being one half of that caused when theultimate load is exerted. lVhen the latter is eXerted, the lower edge ofthe spring abuts substantially simultaneously upon the spring abutmentto which corresponds the line N PN'.

For the manufacture of the described spring steel bands may be usedwhich are either of substantially uniform width and varying thickness orof varying width and uniform thickness or, finally, of both varyingwidth and varying thickness. Preferably the spring is manufactured froma steel band that possesses a substantially uniform width and athickness varving in such a. nianner, that the coils of the spring,except its unelastic end portions, increase in thickness from the inmostcoil to inclusively the outmost one. Of all conical spiral springs ofthe same power a spring of this construction occupies the smallestspace.

'Vhat claim and desire to secure by Letters Patent, is

1. A conical spiral spring having a graduated cross section decreasingfrom its base to its tip with said graduated cross section so related tothe pitch with which said spring is wound that the coils thereof abut onone spring abutment at least approximately simultaneously, upon theultimate load being exerted.

2. A conical spiral spring having a graduat-ed cross section decreasingfrom its base to its tip with said graduated cross section so related tothe pitch with which said spring is wound that the coils thereof abutonone spring abutment at least approximately simultaneously, upon theultimate load being exerted, the pitch being such that each of saidcoils of said spring in loaded condition is displaced an equal fractionof the distance of said coils from the one spring abutment in the restposition, said fraction being the ratio of the load applied to effectsaid displacement to the ultimate load.

SIEGFRIED GROSS.

IGG

